Incorporating Information About Edge Effects When Simulating Lithofacies

Some years ago, earth scientists came to realize that knowing more about the geology of an orebody or an oil reservoir makes it easier to make the appropriate decisions concerning mine planning or reservoir exploitation. Geostatistical techniques for simulating lithofacies—that is, the geometry of the geology—were developed as a result of this. These methods should be able to produce geological images that respect not only the anisotropies of the different lithofacies but also their spatial layout relative to one another. While indicator variograms ensure that anisotropies are respected, another tool needs to be incorporated in the simulation technique to reflect the relative spatial layout of the different lithofacies. We propose to use the concept of edge effects that define the position of one lithofacies relative to another. Simple tests using direct and cross indicator variograms confirm the presence or absence of edge effects. We investigate if and how edge effect information can be incorporated in the different indicator simulation techniques—sequential indicator simulations, simulated annealing, the truncated Gaussian method and plurigaussian simulations. Results show that the choice of simulation method must be guided by the edge effect characteristics of the experimental lithologic data.     

Maturity modelling integrated with apatite fission-track dating: Implications for the thermal history of the Mid-Polish Trough (Poland)

The Mid-Polish Trough (MPT) is situated in the easternmost part of the Central European Basin System (CEBS) and stretches NW–SE across the Polish Basin. It was characterised by pronounced subsidence and thick sediment accumulation between the Permian and the Late Cretaceous. Late Cretaceous–early Paleogene basin inversion led to the formation of the Mid-Polish Swell (MPS). The study area is located within the Pomeranian segment of the MPT/MPS (NW Poland) and experienced up to 7 km Permian-Mesozoic subsidence. PetroMod 1-D modelling was performed on several well-sections in order to study Permian to recent burial-uplift evolution. The modelling was calibrated with new vitrinite reflectance (VR_r) data and allowed to constrain the magnitude of uplift and related erosion as well as provided a first overview of the temperature history. The base of the studied Permian–Mesozoic successions attained maximum burial depths of 4800–5400 m before the onset of the inversion, less than in the axial trough area. The thickness of pre- and most probably also syn-inversion Upper Cretaceous deposits is estimated as 300 m. Erosion associated with inversion processes removed between 900 and 1400 m of the Mesozoic sediments, i.e. 1000–1500 m less than in the most inverted central part of the trough. VR_r data suggest constant Permian–Mesozoic heat flows corresponding to present-day values (40–45 mW/m²). Apatite fission-track (AFT) ages modelled with the PetroMod module PetroTracks show a good fit with AFT ages directly measured on well samples, and further support the assumption of steady heat flow in the range 40–45 mW/m². Palaeotemperatures appear to have decreased towards the East European Craton margin, which is compatible with the present day distribution of heat flow. Thermal history modelling shows a relatively simple Permian–Mesozoic heat flow pattern in the Pomeranian segment of the MPT. Such a scenario implies that the present-day heat flow distribution has not changed essentially since Mesozoic times.     

模拟退火法及其在抗差估计中的应用

抗差估计结果的好坏与初值的选取密切相关。当迭代初值偏离较大时,ρ函数不是严凸时,采取的选权迭代法往往不能获得全局最优值,而只能得到局部的最优解。本文提出一种新的抗差估计求解过程,即把它看作是关于未知参数的全局最优化问题,应用模拟退火法进行求解。计算结果表明:相对于传统的选权迭代法,模拟退火法对初值的选取不敏感,能给出全局最优值。     

Timing and mechanisms for the generation and modification of the anomalous topography of the Borborema Province,northeastern Brazil

The results of apatite fission-track analysis in 14 granitic-gneissic samples from two regional transects across the Borborema Plateau, northeastern Brazil, show evidence for two dominant paleothermal events: a Late Cretaceous cooling event beginning sometime between 100 and 90 Ma, and a second cooling event in the Neogene. The distribution of the fission-track results suggests that the cooling events have a broad regional expression and are consistent with the geologic record in the Araripe Basin, western Borborema Province, which attests to a post-Albian uplift of the whole region. We hypothesize that the first event is due to the uplift and denudation of regional, permanent topography generated after the breakup of Brazil and Africa. Such topography is predicted by models of continental margin extension in which continental lithosphere thinning is followed by thickening of the adjacent hinterland lithosphere and crust (Kusznir, N.J., Karner, G.D., 2007. Continental lithospheric thinning and breakup in response to upwelling divergent mantle flow: application to the Woodlark, Newfoundland and Iberia margins. In: Karner, G.D., Manatschal, G., Pinheiro, L. (Eds), Imaging, mapping and modeling continental lithosphere extension and breakup. Special Publication 282, Geological Society, London, pp. 389–419.). In northeastern Brazil, this extension-engendered topography may have been amplified by magmatic underplating related to the Saint Helena and Ascension plumes. The Miocene cooling event (20–0 Ma) occurred at a time characterized by the transition from carbonate ramp to progradational clastic systems on the Pernambuco–Paraíba margin and the offshore Potiguar Basin. This same stratigraphic response characterizes the Neogene stratigraphy of many passive margins and attests to a global increase in the delivery of clastics to margins, the simplest explanation of which is a climate change that accentuated erosion of pre-existing topography. Thus, the present rugged landscape of northeastern Brazil is interpreted to be a product of this younger denudation event. A corollary of this study is that the history, distribution and delivery of clastics to the northern and northeastern margins of Brazil are a function of the regional development of the continental landscape during the Late Cenozoic.     

On optimization algorithms for the reservoir oil well placement problem

Determining optimal locations and operation parameters for wells in oil and gas reservoirs has a potentially high economic impact. Finding these optima depends on a complex combination of geological, petrophysical, flow regimen, and economical parameters that are hard to grasp intuitively. On the other hand, automatic approaches have in the past been hampered by the overwhelming computational cost of running thousands of potential cases using reservoir simulators, given that each of these runs can take on the order of hours. Therefore, the key issue to such automatic optimization is the development of algorithms that find good solutions with a minimum number of function evaluations. In this work, we compare and analyze the efficiency, effectiveness, and reliability of several optimization algorithms for the well placement problem. In particular, we consider the simultaneous perturbation stochastic approximation (SPSA), finite difference gradient (FDG), and very fast simulated annealing (VFSA) algorithms. None of these algorithms guarantees to find the optimal solution, but we show that both SPSA and VFSA are very efficient in finding nearly optimal solutions with a high probability. We illustrate this with a set of numerical experiments based on real data for single and multiple well placement problems.     

用转换函数研究珠峰站地壳结构

[STBZ][ZW（*][HT6H]〓收稿日期：;修回日期：. *基金项目：[HT6SS][ZK（]国家重点基础研究发展计划项目“青藏高原形成对全球变化的响应与适应对策”（编号：2005CB422001）;中国科学院知识创新工程重要方向项目“青藏高原内陆俯冲与造山作用”（编号：KZCX3 SW 143）资助.[ZK）] [HT6H]〓作者简介：[HT6SS]（1983 ）,男,海南儋州人,硕士研究生,主要从事地震波传播理论研究.[WT6HZ]E mail:[WT6BZ]youliangsu@yahoo.com.cn[ZW）] [HT4F][HT5K]（）[JZ）] [HT5H][GK2] 摘〓要：[HT5K]为开展高喜马拉雅地区地质构造—气候反馈作用的研究,中国科学院青藏高原研究所于2004年开始在珠峰地区建立了综合观测研究站,并于2004年下半年开始相继开展了大气边界层（含辐射和土壤观测）、大气湍流和辐射系统、风温廓线、无线电探空系统、沙尘暴观测、冰川变化等大气科学观测研究、地表过程的环境研究和地球动力学研究。为了解珠峰站下方的地质构造,于2005年8月在综合观测研究站布设了宽频带地震仪（记录器为Reftek130,摆为STS2）,并于2006年5月取得首批数据。利用宽频带地震仪提供的三分量地震波形记录,应用转换函数及快速模拟退火算法对珠峰站下的地壳横波速度结构进行了反演。反演结果表明,珠峰站的莫霍（Moho）面深度在70 km,地壳结构复杂,尤其在中上地壳,明显呈高低速互层结构,反映了板块边界处构造活动、物质交换活跃,表明这些地区还未达到均衡。为高喜马拉雅地区地质构造—气候反馈作用的研究提供地球物理依据。     

阿尔金山北段阿克塞—当金山口一带新生代山体抬升和剥蚀的裂变径迹证据

阿尔金山北段阿克塞—当金山口一带的裂变径迹测年证据表明,该地区于9～7 Ma以来发生过快速抬升和剥蚀,并且一直持续形成了现今所见的阿尔金山。新生代以来至少经历了三次抬升:早期43.6～24.3Ma、中期19.6～13.6 Ma、晚期9～7 Ma。抬升速率先缓慢、后相对快速,9～7 Ma以来的抬升速率为0.94 mm/a。晚期的构造拾升可能与阿尔金断裂带左行走滑活动有关,而与相邻的柴达木盆地北缘地区的构造抬升并不一致。     

基于交通网络的乡村中小学优化布局

合理规划中小学布局是优化教育资源配置、提高办学效益以及实现教育均衡发展的重要途径。本研究针对中国乡村建设的需要和中国多山的地理环境,考虑山地环境对乡村中小学选址的影响,构建多山环境下乡村中小学的区位模型,运用地理信息科学方法,以Visual Studio. Net 2010为开发平台,使用C#语言和ArcGIS Engine 10.0组件库,同时结合MATLAB编程,开发出基于交通网络的乡村中小学区位优化系统。最后将系统应用于贵州省某镇的小学布局优化中,分别在只考虑已有道路、假设道路可升级、假设道路可新建或升级3种情景下,通过改进的模拟退火算法,确定新建学校的最佳位置,以及新道路的修建和原有道路的升级情况,从而得到不同情景下各居民点学生的上学耗时。结果表明,交通网络对乡村中小学布局优化具有重要影响,改善交通网络条件能够有效提高学生的就学效率上学速度。     

区域特性约束下的油藏物性模拟

为了提高油藏物性模拟的精度,本文提出了包含两个约束条件的目标函数,考虑在既满足井条件与空间结构变化,同时又满足油田范围内观测到的油藏物理性质的约束下,应用模拟退火算法,对孔隙度的空间分布进行预测模拟.由于目标函数有效地结合了静、动态信息,从而降低了模拟结果的不确定性,提高了模型的精度.合成数据的油藏物性模拟试验表明,该方法收敛快、稳定性好,模拟的结果令人满意.     

合肥盆地构造演化：磷灰石裂变径迹的多元动力学模拟

对合肥盆地中部肥西县打子塘地区圆筒山组砂岩（J2y）的磷灰石裂变径迹（AFT）分析表明,其FT年龄为（32.5±2.4）Ma（22个颗粒的平均）,明显小于其地层的年龄（176～168 Ma）;围限径迹长度为（12.43±0.18）μm（126个径迹长度的平均值）,为单峰式分布。模拟热史主要为5段：距今176～152 Ma,冷却速率为-21.4℃/Ma;距今152～85 Ma,冷却速率为-0.1℃/Ma;距今85～32 Ma,冷却速率为1.4℃/Ma;距今32～10 Ma,冷却速率为1.6℃/Ma;10 Ma至今,冷却速率为5.0℃/Ma,这5个阶段分别对应了沉积物快速沉降加热、盆地趋于构造热稳定、盆地较快速抬升冷却和快速抬升冷却等演化阶段。沉积物快速加热阶段（176～152 Ma）反映了大别造山晚期山根拆沉阶段与盆地挤压、快速沉降和加热作用,构造热稳定阶段（152～85 Ma）反映了大别造山带热隆伸展和岩浆作用,冷却阶段（85～25 Ma）代表了郯庐断裂的走滑拉张作用与区域性断陷伸展（K2—E）取代热隆伸展体制与早白垩世的岩浆活动。最后一阶段（25 Ma以来）则为合肥盆地的挤压抬升、快速剥露阶段。